The present invention is directed to a composite material and a process for making the composite material. The composite material may be breathable and is formed from at least one non-elastic film layer, at least one non-elastic neckable material, and at least one layer of an elastic material. Sheet layers of at least one non-elastic neckable material laminated to at least one non-elastic film are combined to form a necked laminate defining longitudinal and transverse dimensions wherein the necked laminate is extensible and retractable in at least one dimension without significantly reducing the breathability and/or liquid barrier properties of the film layer. The necked laminate extensibility and retractability is the result of striated rugosities in, for instance, the longitudinal dimension of the film layer which enables the necked laminate to have an amount of extensibility and retractability in the transverse dimension. Addition of at least one layer of an elastic material to the necked laminate to form a composite material provides stretch and recovery which was not present in the necked laminate while still maintaining breathability and barrier properties.
Composite materials of multiple sheet layers of, for instance, film and nonwoven web layers, are known to be useful in such articles as diapers, training pants, incontinence garments, mattress pads, wipers, feminine care products such as sanitary napkins, in medical applications such as surgical drapes, gowns and facemasks, articles of clothing or portions thereof including workwear and lab coats, and the like.
These composite materials are made such that the article can be produced with relatively low cost and are thus disposable after only one or a few uses. Much research and development continues, however, to achieve xe2x80x9ccloth-likexe2x80x9d visual and tactile qualities in these articles without sacrificing breathability and low cost, while also providing an article that is liquid-impermeable. In particular, one disadvantage of such articles is that the material used to make the article does not xe2x80x9cgivexe2x80x9d like, for instance, a fabric made from cotton, which due to its fiber and yarn structure, has a natural ability to extend and retract. These properties are necessary to allow the article to conform to the user""s body, thereby feeling and appearing to be more xe2x80x9ccloth-likexe2x80x9d. Even when the article xe2x80x9cgivesxe2x80x9d it may quickly lose its shape if it does not exhibit stretch and recovery. One known solution to this problem has been to use an elastomeric or elastic material to form, for instance, the film layer of a film/nonwoven laminate. If breathability is attained by stretching a filled elastic film to form micropores, there are problems associated with maintaining breathability of filled elastic films since the recovery of the elastic material after stretching generally closes or partially closes the micropores which had been created for breathability.
Layers of a nonwoven web have been necked (as defined below) prior to applying an elastomeric sheet made using an elastomeric polymer as described in, for instance, commonly assigned U.S. Pat. No. 5,336,545 to Morman. Necking of the nonwoven web allowed it to extend in the transverse direction, but it would not recover without attachment of the elastic sheet.
Prior art laminates made from non-elastic materials which were used as, for example, diaper outer cover would not stretch in all directions and still be breathable through a non-elastic microporous film. Further, the prior art laminates of non-elastic materials that have been used in waistband components in articles such as diapers, have been made to be more conformable by first stretching an elastic waistband, then attaching the laminate to the stretched waistband such that when the waistband retracts, it draws in the laminate. A problem with this design is that the laminate is difficult to gather or bunch and the resulting product has minimal extensibility and retractability. Such bunched laminates are also very difficult to fabricate, have a cheap appearance and are uncomfortable when in contact with the body.
The present invention avoids these and other difficulties by providing an inexpensive composite material of a non-elastic necked laminate and at one elastic material which achieves stretch and recovery without compromising other properties such as breathability, liquid barrier properties and strength.
The present invention is directed to a composite material and a process for making the material. The composite material may be breathable and is formed from at least one layer of an elastic material and a necked laminate of sheet layers. The sheet layers include at least one non-elastic neckable material laminated to at least one non-elastic film defining a longitudinal and transverse dimension wherein the laminate is extensible and retractable in at least one dimension without significantly reducing the breathability and/or liquid barrier properties of the film layer. This laminate extensibility and retractability is the result of striated rugosities in, for instance, the longitudinal dimension of the film layer which enables the necked laminate to have an amount of extensibility and retractability in the transverse dimension. A breathable laminate may be made by first partially stretching a filled non-elastic film layer, attaching a non-elastic neckable layer to form a laminate and then stretching the laminate to neck the laminate and lengthen the film to its desired fully stretched configuration. Attachment of at least one layer of an elastic material to the necked laminate further provides stretch and recovery in at least one dimension.